84 



PHYSIOLOGY 



CHAP. 



VI. The Pancreas is a long gland, of irregular prismatic shape ; 

 its external secretion is conveyed to the duodenum -by the canal 

 or duct of Wirsung, which runs along the entire length of the 

 gland, buried in its substance. Its size and weight differ consider- 

 ably in different individuals. It is 12-13 cm. long, with a 

 maximum diameter of 12-25 mm. According to Krause, it weighs 

 66-102 grins., but Meckel gives a maximum weight of 180 grins., 

 and Sommering a minimal weight of 45 grins. Its specific gravity 

 is 1-046. 



From its structure the pancreas must be regarded as an 

 acino-tubular gland, resembling the salivary glands, but with 



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FIG. 25. Section of human pancreas. (Bohm and \. Davidoff.) D, principal duct; C, connective 

 tissue ; A, alveolus or acinus ; c.c, centro-acinar cells of Langerhans ; P, commencement of 

 duct ; p, small alveolus without central cells. 



lobes and lobules more loosely knit together by connective tissue. 

 The secretory alveoli consist of short tubules, which in a section 

 resemble rounded acini. The primary and secondary ducts are 

 lined with simple columnar epithelium, the cells of which become 

 lower in the small ducts, till where these arise in the alveoli 

 they are reduced to narrow, flattened, spindle-shaped cells (Fig. 25). 

 The number of ducts in the pancreas is not constant even in 

 a series of the same animals. In man they are usually two, the 

 principal, or duct of Wirsung, and the accessory, or duct of 

 Santorini. The latter may be absent (Hess), in any case it is 

 always very minute in the adult, while in the early stages of 

 development it is larger than Wirsung's duct. In the dog there 

 are invariably two ducts, and in a certain number of cases (30 per 



